Microorganisms are very small living creatures, that are much too small to be seen with the naked eye. There are four types of microorganisms: bacteria, viruses, parasites and fungi. In the previous articles, bacteria and fungi were defined. This week’s series will highlight viruses. Viruses are the smallest of the microbial contaminants. They consist of genetic material wrapped with an outer layer of protein. While a virus cannot reproduce outside a living cell, once inside, it will reproduce more viruses. Viruses are responsible for several foodborne illnesses such as hepatitis A, and infections caused by the norwalk virus and rotavirus. Rotavirus infections are the leading cause of severe gastroenteritis among infants and young children worldwide. Viruses that infect the gastrointestinal tract are usually transmitted by food or water. Infections results from: consumption of food contaminated by a food handler carrying the virus; consumption of raw seafood taken from waters polluted by human wastes; or drinking polluted water. Hepatitis is a mild illness with symptoms of sudden onset of fever, nausea, loss of appetite and abdominal discomfort and is followed by jaundice. The incubation time may be 10-50 days. During the middle of the incubation period, it can be transmitted to others. Usually, recovery is complete in one to two weeks. The center for Disease Control recorded 25,000 cases per year of Hepatitis A from 1980-2001. Adjusting for under reporting reveals 263,000 per year. One of the largest outbreaks occurred in 2003, which involved green onions imported from Mexico. More than 700 people in four states were infected with hepatitis A. Person-to-person transmission, as well as foodborne and waterborne transmission, occur. Adults are more susceptible to this illness. Foods become contaminated by food handlers who do not follow good personal hygiene practices or contaminated water. Cold cuts, sandwiches, salads, fruits, shellfish, and iced drinks are commonly implicated in outbreaks. Contamination of foods by infected workers in food processing plants and restaurants is common. To control hepatitis A,wash hands thoroughly and after using the restroom or diapering infants. Also, harvest shelfish from unpolluted waters. Noroviruses or norwalk viruses are a group of viruses that cause the stomach flu or gastroenteritis in people. The symptoms of norovirus illness usually include nausea, vomiting, diarrhea and some stomach cramping. Sometimes people additionally have a low-grade fever, chills, headache, muscle aches and a general sense of tiredness. The illness often begins about 24 to 48 hours after ingestion of the virus, but symptoms can appear as early as 12 hours after exposure. The illness is usually brief, with symptoms lasting only about one or two days and have no long-term health effects related to the illness. However, sometimes people are unable to drink enough liquids to replace the liquids they lost because of vomiting and diarrhea. These persons can become dehydrated and may need special medical attention. This problem with dehydration is usually only seen among the very young, the elderly, and persons with weakened immune systems. Noroviruses are found in the stool or vomit of infected people. People can become infected with the virus in several ways, including: eating food or drinking liquids that are contaminated with norovirus; touching surfaces or objects contaminated with norovirus, and then placing their hand in their mouth; and having direct contact with another person who is infected and showing symptoms. This virus is very contagious and can spread rapidly. People infected with norovirus are contagious from the moment they begin feeling ill to at least three days after recovery. Some people may be contagious for as long as two weeks after recovery. Therefore, it is particularly important for people to use good hand washing and other hygienic practices after they have recently recovered from norovirus illness. You can decrease your chance of coming in contact with noroviruses by following these preventive steps: ‘ Frequently wash hands, especially after changing diapers and before eating or preparing food; ‘ Carefully wash fruits and vegetables; ‘ Steam oysters before eating them; ‘ Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a bleach water solution; and ‘ Immediately remove and wash clothing or linens that may be contaminated with a virus after an episode of illness. Another highly contagious virus is the rotavirus. This virus most often infects infants and young children. In children ages three months to two years, it is one of the most common causes of diarrhea. In the United States, it leads to outbreaks of diarrhea during the winter and spring months. It is particularly a problem in child-care centers, children’s hospitals and public schools. Almost all children have had a rotavirus infection by the time they are five years old. Children with a rotavirus infection have fever, nausea and vomiting which are often followed by abdominal cramps and frequent, watery diarrhea. Children who are infected may also have a runny nose. Sometimes, the diarrhea that accompanies a rotavirus infection is so severe that it can quickly lead to dehydration. Signs of dehydration include: thirst, irritability, restlessness, lethargy, sunken eyes, a dry mouth and tongue, dry skin, fewer trips to the bathroom to urinate, and in infants, a dry diaper for several hours. Like norovirus, rotavirus may be prevented through frequent handwashing and cleaning and sanitizing surfaces that the virus has come in contact with. Children who are infected should stay home from child-care centers or schools until their diarrhea has resolved. Child-care centers and schools must clean and sanitize all contact surfaces: desk, door knobs, etc. To combat all foodborne illnesses, one must take into practices the ‘four C’s” of Food Safety’clean, don’t cross-contaminate, cook and chill. Keep everything clean, wash hands often, keep all food preparation surfaces and utensils clean and sanitized. Don’t cross-contaminate. Keep raw foods away from fresh foods. Always cook foods long enough to kill bacteria that may be present. Cook all meats to the recommended internal temperature. Keep cold foods cold and hot foods hot. Never leave perishable foods in the danger temperature zone of 40-140 degrees for more than two hours. Keep refrigerator temperatures at 40 degrees farenheit or below and freezer temperature at 0 degrees farenheit or below.